Multifunctional acrylic monomers of high functionality, of at least three and possibly ranging up to six, in terms of acrylic groups already exist and are used in coating applications such as varnishes or inks for increasing the crosslinking density and the performance levels related to this increase, such as chemical resistance or hardness.
However, the existing acrylic multifunctional monomers lead to poor flexibility, in particular for use in coatings, said flexibility being defined here in terms of resistance to folding determined by the folding test on a cylindrical support. Thus, the hardness/flexibility compromise is poor, as is the adhesion to substrates, for example in applications for coatings such as varnishes or inks. This is essentially caused by an excessively high degree of crosslinking (which may be expressed by a density of crosslinking nodes per unit of weight) and shrinkage related to the large number of reacted unsaturations. Moreover, these monomers are based on specific multifunctional polyols such as polyol diethers of lower functionality, for example ditrimethylol propane (DiTMP) or dipentaerythritol (DiPE), these products being difficult to access and costing many times that of the starting polyols, for example for DiTMP relative to trimethylol propane (TMP) or for DiPE relative to pentaerythritol (PE). A practical, simpler and less expensive solution is thus sought, thus using starting polyols such as TMP or PE, said solution simultaneously needing to solve the technical problems and drawbacks observed above with the existing products.
The possible recourse to alkoxylation of said starting polyols, which would make it possible to reduce the crosslinking density of the products obtained, moreover brings about a loss of reactivity, which is unacceptable since reactivity is one of the essential required properties, if not the essential property of these monomers.